Recently I was doing some clean up (deleting) my emacs buffers and I has a kind of boring task having to open each buffer and kill it (one at a time).

But I found that that you can do it quickly with Helm.
If you run M-x helm-mini (I have it mapped to C-2), you can see a list of open buffers, and by scrolling through the list and selecting the ones you want to delete with C-Space.

When you have them all selected, just press M-S-d / M-D, and all selected buffers will be deleted and Helm closes.